bims-pisump 2018-08-19 papers

Issue of 2018–08–19
four papers selected by
Vera S. Bogdanova, ИЦиГ СО РАН

Plant Physiol Biochem. 2018 Aug 06. pii: S0981-9428(18)30339-5. [Epub ahead of print]130 529-541

Proteomics unravel the regulating role of salicylic acid in soybean under yield limiting drought stress.

Marisha Sharma, Sunil K Gupta, Baisakhi Majumder, Vivek K Maurya, Farah Deeba, Afroz Alam, Vivek Pandey.

Drought is a major concern for sustainable yield under changing environment. Soybean, an economically important oil and protein crop, is prone to drought resulting in yield instability. Salicylic acid (SA), a multifaceted growth hormone, modulates a series of parallel processes to confer drought tolerance thereby relieving yield limitations. The present study was performed in soybean plants treated with SA (0.5 mM) through seed pretreatment under drought regimes: severe stress (50% RWC) and moderate stress (75% RWC), and rehydration. Differential leaf proteome profiling with morphological, physiological and antioxidative metabolism studies were performed at two developmental stages (vegetative and flowering). This explained the tolerance attribution to soybean throughout the development attaining yield stability. Abundance of proteins involved in photosynthesis and ATP synthesis generated energy driving metabolic processes towards plant growth, development and stress acclimation. Carbon (C) metabolism proteins involved in growth, osmoregulation and C partition relieved drought-induced C impairment under SA. Defensive mechanisms against redox imbalance and protein misfolding and degradation under stress were enhanced as depicted by the abundance of proteins involved in redox balance and protein synthesis, assembly and degradation at vegetative stage. Redox signaling in chloroplast and its interplay with SA signaling triggered different defense responses as shown through thioredoxin protein abundance. Amino acid metabolism proteins abundance resulted in increased osmoprotectants accumulation like proline at initial stage which contributed later towards N (nitrogen) remobilization to developing sink. At later stage, abundance of these proteins maintained redox homeostasis and N remobilization for improved sink strength. The redox homeostasis was supported by the increased antioxidative metabolism in SA treated plants. The downregulation of proteins at flowering also contributed towards N remobilization. Yield potential was improved by SA under drought through acclimation with enhanced N and C remobilization to sink as demonstrated by increased yield parameters like seed number and weight per plant, thousand seed weight and harvest index. The potential of SA in conferring drought tolerance to plants to maintain sustainable yield possess future research interests.

Keywords: Drought; Salicylic acid; Sink; Soybean; Tolerance; Yield

DOI: https://doi.org/10.1016/j.plaphy.2018.08.001

Plant Cell Rep. 2018 Aug 11.

Physiological and transcriptomic responses of reproductive stage soybean to drought stress.

Congshan Xu, Chao Xia, Zhiqiang Xia, Xiangjun Zhou, Jing Huang, Zhiqiang Huang, Yan Liu, Yiwei Jiang, Shaun Casteel, Cankui Zhang.

KEY MESSAGE: The dynamic alterations of the physiological and molecular processes in reproductive stage soybean indicated the dramatic impact caused by drought. Drought is a major abiotic stress that limits soybean (Glycine max) production. Most prior studies were focused on either model species or crops that are at their vegetative stages. It is known that the reproductive stage of soybean is more susceptible to drought. Therefore, an understanding on the responsive mechanisms during this stage will not only be important for basic plant physiology, but the knowledge can also be used for crop improvement via either genetic engineering or molecular breeding. In this study, physiological measurements and RNA-Seq analysis were used to dissect the metabolic alterations and molecular responses in the leaves of soybean grown at drought condition. Photosynthesis rate, stomata conductance, transpiration, and water potential were reduced. The activities of SOD and CAT were increased, while the activity of POD stayed unchanged. A total of 2771 annotated genes with at least twofold changes were found to be differentially expressed in the drought-stressed plants in which 1798 genes were upregulated and 973 were downregulated. Via KEGG analysis, these genes were assigned to multiple molecular pathways, including ABA biogenesis, compatible compound accumulation, secondary metabolite synthesis, fatty acid desaturation, plant transcription factors, etc. The large number of differentially expressed genes and the diverse pathways indicated that soybean employs complicated mechanisms to cope with drought. Some of the identified genes and pathways can be used as targets for genetic engineering or molecular breeding to improve drought resistance in soybean.

Keywords: Drought; Reproductive stage; Soybean; Transcriptome

DOI: https://doi.org/10.1007/s00299-018-2332-3

Plant Cell. 2018 Aug 10. pii: tpc.00312.2018. [Epub ahead of print]

Plastidial phosphoglucose isomerase is an important determinant of seed yield through involvement in gibberellin-mediated reproductive development and biosynthesis of storage reserves in Arabidopsis.

Abdellatif Bahaji, Goizeder Almagro, Ignacio Ezquer, Samuel Gámez-Arcas, Ángela María Sánchez-López, Francisco José Muñoz, Ramon José Barrio, M Carmen Sampedro, Nuria De Diego, Lukáš Spíchal, Karel Dolezal, Danuše Tarkowská, Elisabetta Caporali, Marta Adelina Mendes, Edurne Baroja-Fernández, Javier Pozueta-Romero.

The plastid-localized phosphoglucose isomerase isoform PGI1 is an important determinant of growth in Arabidopsis, probably due to its involvement in synthesis of plastidial isoprenoid derived hormones. We have tested the possibility that it also influences seed yields, and several associated hypotheses. Gene expression analyses showed that PGI1 is strongly expressed in maturing seed embryos and vascular tissues. PGI1-null pgi1-2 plants had ca. 60% lower seed yields than wild type (WT) plants. They produced fewer inflorescences, and thus fewer siliques and seeds per plant. These traits were associated with low contents of bioactive gibberellins (GAs). Accordingly, WT phenotypes could be restored by exogenous GA application. pgi1-2 seeds were lighter and accumulated ca. 50% less fatty acids (FAs) and ca. 35% less proteins than WT seeds. Seeds of CK-deficient 35S:AtCKX1 and GA-deficient ga20ox1 ga20ox2 mutants did not accumulate low levels of FAs, and exogenous application of BAP and GAs did not rescue the reduced weight and FA content of pgi1-2 seeds. Seeds from reciprocal crosses between pgi1-2 and WT plants accumulated WT levels of FAs and proteins. Our results show that PGI1 is an important determinant of Arabidopsis seed yield due to its involvement in two processes: GA-mediated reproductive development and the metabolic conversion of plastidial glucose-6-phosphate to storage reserves in the embryo.

DOI: https://doi.org/10.1105/tpc.18.00312

Planta. 2018 Aug 11.

AgMYB2 transcription factor is involved in the regulation of anthocyanin biosynthesis in purple celery (Apium graveolens L.).

Kai Feng, Jie-Xia Liu, Ao-Qi Duan, Tong Li, Qing-Qing Yang, Zhi-Sheng Xu, Ai-Sheng Xiong.

MAIN CONCLUSION: This study showed that an R2R3-MYB transcription factor, AgMYB2, functions in anthocyanin biosynthesis and accumulation in purple celery. Anthocyanins are involved in tissue coloration and stress response in plants. Foods containing high anthocyanin content are also beneficial to human health. Purple celery accumulated amounts of anthocyanins in the petioles. The biosynthesis of anthocyanin in plants is mainly regulated by the R2R3-MYB transcription factor (TF). However, the R2R3-MYB TF that controls anthocyanin accumulation in purple celery remains unclear. In this study, an R2R3-MYB TF gene, AgMYB2, was cloned from purple celery and characterized as anthocyanin biosynthetic regulator. Sequence analysis indicated that AgMYB2 contained highly conserved R2R3 domain and two anthocyanin characteristic motifs, ANDV motif and KPRPR[S/T]F motif. The relative expression level of AgMYB2 in purple celery was significantly higher than that in non-purple celery at three developmental stages. Heterologous expression of AgMYB2 in Arabidopsis generated more anthocyanins and resulted in dark-purple leaves and flowers. The expression levels of anthocyanin biosynthetic genes and the antioxidant activity of transgenic Arabidopsis carrying AgMYB2 were up-regulated. The determination of anthocyanin glycosylation activity of Arabidopsis crude enzyme verified the anthocyanin biosynthesis regulatory function of AgMYB2 at the protein level. The interaction between AgMYB2 and bHLH proteins was shown by yeast two-hybrid assay. The results will help to elucidate the molecular mechanism of anthocyanin biosynthesis in purple celery and provide an approach for cultivating plants with high anthocyanin content.

Keywords: Anthocyanin; Celery; Expression level; Overexpression; R2R3-MYB; Regulation

DOI: https://doi.org/10.1007/s00425-018-2977-8